Generation, characterization, and application of caprine herpesvirus 1 secreted glycoprotein D

Caprine herpesvirus 1 (CpHV-1), a member of the Herpesvirales order,Herpesviridae family, Alphaherpesvirinae subfamily, and Simplexvirus genus, is classicallyassociated with two distinct clinical syndromes. In kids, CpHV-1 induces severe systemicdisease with high morbidity and mortality, whereas in adult goats, the infection leadsto genital lesions such as vulvovaginitis or balanoposthitis, with abortions occurringmainly in the second half of gestation. CpHV-1 shares several biological characteristicswith human herpesvirus 2, including molecular features, tropism for vaginal epithelium,genital lesion nature, and latency in the sacral ganglia. These features make CpHV-1-infected goats a reliable animal model for studying human herpesvirus-induced genitaldisease, relevant for pathogenic research, as well as the development of new vaccinesand antiviral agents. Recent full sequencing of the CpHV-1 genome has identified atleast 10 genes encoding glycoproteins. Among these, glycoprotein D (gD) has beencharacterized but not yet exploited for immunogenic or diagnostic purposes. In thisstudy, the structural features of CpHV-1 gD were predicted using in silico analysis. Atruncated version of gD lacking the transmembrane domain (secreted glycoprotein D[Sec-gD]) was subsequently generated and expressed in mammalian cells, enabling itssecretion into the culture medium. Despite the structural modifications, Sec-gD retaineda conserved glycosylation pattern, as confirmed by N-glycosylation mutants generationand peptide-N-glycosidase F treatment. Furthermore, the antigenic properties of Sec-gDwere preserved, as demonstrated by reverse serum neutralization assays. Notably, theculture supernatant containing Sec-gD was directly usable in diagnostic enzyme-linkedimmunosorbent assays, supporting its potential as a valuable tool for both diagnosticand immunization strategies.